NAME

Capsicum — lightweight OS capability and sandbox framework

SYNOPSIS

optionsCAPABILITY_MODEoptionsCAPABILITIESoptionsPROCDESC

DESCRIPTION

Capsicum is a lightweight OS capability and sandbox framework implementing a hybrid
capability system model. Capsicum can be used for application and library
compartmentalisation, the decomposition of larger bodies of software into isolated
(sandboxed) components in order to implement security policies and limit the impact of
software vulnerabilities.
Capsicum provides two core kernel primitives:
capability mode
A process mode, entered by invoking cap_enter(2), in which access to global OS
namespaces (such as the file system and PID namespaces) is restricted; only
explicitly delegated rights, referenced by memory mappings or file descriptors, may
be used. Once set, the flag is inherited by future children processes, and may not
be cleared.
capabilities
Limit operations that can be called on file descriptors. For example, a file
descriptor returned by open(2) may be refined using cap_rights_limit(2) so that only
read(2) and write(2) can be called, but not fchmod(2). The complete list of the
capability rights can be found in the rights(4) manual page.
In some cases, Capsicum requires use of alternatives to traditional POSIX APIs in order to
name objects using capabilities rather than global namespaces:
process descriptors
File descriptors representing processes, allowing parent processes to manage child
processes without requiring access to the PID namespace; described in greater detail
in procdesc(4).
anonymous shared memory
An extension to the POSIX shared memory API to support anonymous swap objects
associated with file descriptors; described in greater detail in shm_open(2).